Flip chip and pre-molded clip power modules

Abstract

Devices and methods are disclosed for high power inverter modules with enhanced thermal and mechanical performance, for use in electric vehicles. The disclosed devices feature enlarged clips that cover an entire die, to distribute mechanical forces, thus preventing die cracks for improved reliability. In these power modules, semiconductor dies are sandwiched between a three-layer direct bond metal (DBM) structure and the enlarged clip. A pre-molded clip assembly can be used that includes integrated metalliization to eliminate the need for external wire bonds. Alternatively, semiconductor dies can be inverted in a flip-chip configuration to face a modified DBM structure that integrates the metallization. Simulations of the disclosed power inverters indicate improved efficiency in dissipating heat.

1 . An apparatus, comprising:
 a semiconductor die;   a direct bonded metal (DBM) structure coupled to a first side of the semiconductor die, the DBM structure configured to dissipate heat from the first side of the semiconductor die;   a pre-molded clip assembly coupled to a second side of the semiconductor die; and   a molding compound at least partially encapsulating the semiconductor die, the DBM structure and the pre-molded clip assembly, to form a power module.   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 a lead frame coupled to the integrated metal routing layer; and   a mounting bracket coupled to the DBM structure.   
     
     
         3 . The apparatus of  claim 1 , wherein the pre-molded clip assembly is an encapsulated modular unit. 
     
     
         4 . The apparatus of  claim 1 , wherein the pre-molded clip assembly includes an integrated metal routing layer coupled to a terminal of the semiconductor die. 
     
     
         5 . The apparatus of  claim 1 , wherein the semiconductor die is a silicon carbide (SiC) chip. 
     
     
         6 . The apparatus of  claim 1  wherein the semiconductor die is an insulated gate bipolar transistor (IGBT) chip. 
     
     
         7 . The apparatus of  claim 1 , wherein the semiconductor die is attached to both the DBM structure and the clip by respective layers of sintered silver. 
     
     
         8 . The apparatus of  claim 1 , wherein the semiconductor die is attached to the DBM structure by a layer of sintered silver and to the clip by a layer of a lead-based solder. 
     
     
         9 . The apparatus of  claim 8 , wherein the lead-based solder includes lead selenium silver (PbSnAg). 
     
     
         10 . The apparatus of  claim 1 , wherein the power module is configured as an inverter for use in electric vehicles (EVs) and hybrid electric vehicles (HEVs). 
     
     
         11 . The apparatus of  claim 1 , wherein the DBM includes a Si 3 N 4  ceramic layer. 
     
     
         12 . A pre-molded clip assembly, comprising:
 an encapsulant;   a metal routing layer centered within the encapsulant;   a first metal clip coupled to a lower surface of the metal routing layer and extending through the encapsulant; and   a second metal clip coupled to the lower surface of the metal routing layer and extending through the encapsulant; the second metal clip spaced apart from the first metal clip by an insulating material.   
     
     
         13 . The pre-molded clip assembly of claim  17 , wherein a first end of the metal routing layer is surrounded by the encapsulant, and an opposite end of the metal routing layer extends through the encapsulant to make contact with a first external element. 
     
     
         14 . The pre-molded clip assembly of claim  17  wherein the first metal clip and the second metal clip are configured to make contact with portions of a second external element. 
     
     
         15 . The pre-molded clip assembly of claim  19 , wherein the second external element is a semiconductor die and the apparatus is sized to fit within an electronic power module. 
     
     
         16 . A method, comprising:
 forming a pre-molded clip assembly, including a first encapsulant;   attaching the pre-molded clip assembly to a semiconductor die;   attaching a semiconductor die to a direct bond metal (DBM) structure; and   encapsulating the semiconductor die, the pre-molded clip assembly, and the DBM structure in a second encapsulant to form a power module.   
     
     
         17 . The method of  claim 16 , wherein forming the pre-molded clip assembly includes forming an integrated metal routing layer therein. 
     
     
         18 . The method of  claim 17 , wherein forming the pre-molded clip assembly further includes forming a metal clip between the integrated metal routing layer and the semiconductor die. 
     
     
         19 . The method of  claim 17 , wherein forming the pre-molded clip assembly includes:
 sizing the integrated metal routing layer to be larger than the semiconductor die; and   forming gate and source contacts to the semiconductor die in the integrated metal routing layer.   
     
     
         20 . The method of  claim 17 , wherein the first and second encapsulants are made of similar epoxy molding compounds (EMCs).